Iron bimetallic complexes

Fe—Fe bond can be assigned structures 201 or 202 based on spectral data. The other product of this reaction is 193 (R = r-Bu), however, it is produced in minor amounts. Complexes 199 (R = R = r-Bu, R = Ph, R = r-Bu) were obtained. Reaction of 146 (M = Mo, R = Ph, R = R = Ft, R = r" = Me) with (benzyli-deneacetone)iron carbonyl gives rise to the bimetallic complex 200 (M = Mo), which reacts further with the free phosphole to form the bimetallic heteronuclear sandwich 203. The preferable coordination of the molybdenum atom to the dienic system of the second phosphole nucleus is rather unusual. The molybdenum atom is believed to have a greater tendency to coordinate via the trivalent phosphorus atom than via the dienic system. 

An example of particular interest is the two-fold introduction of M(CO)n moieties at silicon to give HMPA adducts of organometallic analogues of silaallene. It has been shown that this reaction proceeds through the dichlorosilylene complex as intermediate. Both the iron 22 and ruthenium 23 compound and also the bimetallic complex 24 are accessible. 

Bielawski et al. have developed Janus-head dicarbene ligands which are able to act as a bridge between two metal centers, thereby leading to dinuclear complexes of type 96 [58-60] (Fig. 32). More recently homonuclear bimetallic ruthenium(II) and iron(II) complexes 97 have been synthesized. It was hoped that the dicarbene ligand would interconnect the redox-active metal centers, but the... 

Nevertheless, Hossain and coworkers also investigated the carbene transfer reaction using a chiral bimetallic iron-carbene complex, which also exhibits excellent... 

Neutral (cyclobutadiene)iron complexes undergo thermal and photochemical ligand substitution with phosphines, with alkenes such as dimethyl fumarate and dimethyl maleate, and with the nitrosonium cation. Cationic nitrosyl complexes (e.g. 210) undergo ligand substitution by treatment with phosphines. Photolysis of (tetraphenylcyclobutadiene)Fe(CO)3 in THF at -40 °C is reported to give the novel bimetallic complex (214), which reacts with carbon monoxide (140 atm, 80 °C) to regenerate the starting material.An X-ray diffraction analysis of (214 R = Ph, R = t-Bu) reveals a very short Fe-Fe distance of 2.117 A. 

It is difficult to find direct bonding interaction between the ferrocene iron and the second transition metal in the hetero-bimetallic complexes. Only the mono-triphenylphosphine palladium and platinum compounds fc[E2M(PPh3)] (E = O, M = Pd (Scheme 5-14) [79] E = S, M = Pd [268, 269], and Pt [269]) appear to... 

The molecular ions of the bimetallic complex [Cr(CO)5]2AsPh (150) lose consecutively 10 CO groups and the Cr atom leading to CrAsPh . Its tiimetallic analogue 151 also loses consecutively all carbonyl ligands and two iron atoms with the formation of... 

Olefin-coupling reactions of Tj -allyliron complexes with a variety of cationic iron-olefin complexes (ethylene, propene, styrene, etc.) were utilized to give cationic bimetallic complexes with cr,7r-hydrocarbon bridges (80,81). The condensation of simple [FpColefin)]" substrates with Fp(allyl) precursors was extended to the reaction with Fp(l,3-butadi-ene)+. Initial attack at C-1 or C-4 leads to the formation of dinuclear complexes with cr-coordinated and 7r-coordinated Fp fragments, which by subsequent intramolecular condensation could give either cyclohexenyl or cyclopentenyl intermediates. Attack at C-2 yields a dinuclear complex incapable of further intramolecular reaction [Eqs. (6-8)]. 

The bimetallic complex (CO)5Cr =C(OMe)CH2—C6H7-77 - Fe(CO)3 (68a) was synthesized by reacting the anionic carbene precursor with the cationic cyclohexadienyl complex [Fe(7j -cyclohexadienyl)(CO)3]+ (197). Complex 68a is chiral, and a structure determination showed that both enantiomers are present in the unit cell. Deprotonation of a second acidic proton from the position a to the carbene carbon of 68a by -BuLi and subsequent treatment with another equivalent of the iron substrate afforded the trimetallic cr,Tr,7r complex (CO)5Cr=C(OMe)CH C6H7-7 -Fe(CO)3 2 (68b). The complex 68b has three chiral centers and can as a... 

The condensation of Cr(CO)6 with FeCp(CO)2 2-CSCHCHCH and FeCp(CO)2 2-benzofuran is facilitated by the iron fragment and gave the bimetallic complexes 145 and 146 (J60). 

The bimetallic complex [(OC)3Fe(/<-PPh2)2Ru(CO)3] is also an active catalyst for the homogeneous hydroformylation of styrene (393 K, 20 atm, CO/H2 = 1). A synergistic effect between iron and ruthenium was observed and the intact complex was recovered at the end of the reaction. ... 

Iron carbene complexes bearing chirality at the carbene ligand can be generated from optically pure bimetallic (chromium-iron) complexes by the addition of 1 equiv of TMSOTf in the presence of an olefin, which in situ undergoes an asymmetric cyclopropa-nation. Excellent ee s are obtained when the reaction is carried out with em-disubstituted olefins (eq 122). 5... 

It is useful to compare the molecular and electronic stmctures of the bis(imino)pyridine iron dinitrogen complexes with those of the ruthenium congeners reported by Berry and coworkers [32]. Stirring K -( PDI)Ru(q -arene) complexes in non-arene solvents under a dinitrogen atmosphere furnished the bimetallic ruthenium dinitrogen complex [( PDI)Ru]2(P2> l dimeric... 

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